1. Field of the Invention
This invention relates to a novel class of detergent dispersant compounds which inhibit or prevent the formation of sludge or varnish in lubricants intended for use in the crankcase of internal combustion engines, gears and other power transmitting units. More specifically, the invention concerns compounds of the above described type which are prepared by a process offering the economic advantage of avoiding the formation of contaminating inorganic by-products and eliminates the need for special equipment in handling volatile and dangerous materials. The process further has the improved feature of employing a simplified purifying step.
2. Description of the Prior Art
The prior art to which this invention relates are U.S. Pat. Nos. 3,172,892 and 3,272,746, which describe the thermal reaction products of alkenylsuccinic anhydride with amines; and Japanese Pat. No. 7,342,603, which describes the preparation of quaternary ammonium salts from amines and carboxylic acid esters. The latter patent indicates that pyridine and methyl salicylate can be refluxed to yield 1-methylpyridinium salicylate and that the salicylates of Et.sub.3 N.sup.+ Me, PhCH.sub.2 N.sup.+ Et.sub.3, HOCH.sub.2 CH.sub.2 N.sup.+ MeEt.sub.2 ; methyl-ethyl-and propylisoquinolinium cations can be similarly prepared. Also relevant is coassigned U.S. Pat. No. 4,048,080 which describes and claims amine alkenylsuccinic acid or anhydride reaction products which can be used as one of the starting products here. This patent accordingly is incorporated by reference in the present disclosure.